A cohort of 551 persons over age 60 and with isolated systolic hypertension was recruited in 1981-2 for a pilot study on the feasibility of a full scale trial of the effects of stepped care drug treatment on health. Funding for the Systolic Hypertension in the Elderly Project (SHEP) pilot study will end in June 1984; although the initial goal has been achieved, important research questions, many of them new, remain unsettled. The proposed SHIELD study takes advantage of the existing SHEP data base, and continues the randomized, placebo-controlled, double-blind treatment, with certain modifications, in order: 1. To test the safety and efficacy of low dose diuretic treatment with and without beta blocking drugs, in isolated systolic hypertension in the elderly. Specifically, what proportion of patients can be controlled with 12.5 mg of chlorthalidone daily, and does the addition of metroprolol or placebo (also randomly assigned and double-blind) alter the level of blood pressure control, of total and HDL cholesterol, and of side effects. 2. To continue treating this cohort of elderly patients with either drugs or placebo for two additional years in order: a) to validate and extend the incidence estimates for morbidity and mortality, generating hypotheses from trends in various subgroups b) to improve the methods for adverse event monitoring and observe the event rates for the two added years; c) to extend the incidence estimates and identify the risk factors for behavioral dysfunction; and d) to complete the development and testing of the distributed data system. 3. To analyze and report the scientific findings and methodological advances in the medical literature.